同位素位移实验测量

利用光栅光谱仪测量了氢－氘灯谱线的同位素位移。利用具有高分辨、选择性激发等特点的共线快离子束－激光光谱学方法测量了^142-146,148,150Nd^ 同位素位移，结合King-plot和理论计算得到质量位移、场位移和特殊质量位移。     

Optical isotope shifts in neodymium

Isotope shifts have been measured in Nd II from which the shifts between pure configurations 4f ⁴ 6s and 4f ⁴ 5d can be determined. The specific mass shift for such a “transition” was estimated to be + 3 mK for a change of two neutrons. By comparison with electronic X-ray isotope shifts the following values were obtained for the change in the nuclear charge distributionδ〈r ²〉 [fm²]: (142, 144) 0.277; (144, 146) 0.257; (146, 148) 0.286; (148, 150) 0.381; (142, 143) 0.130; (144, 145) 0.111. Field shifts in several optical transitions have been compared with values of ¦ψ(0)¦² obtained from Hartree-Fock wave functions; agreement is good. Other specific mass shifts have been estimated 4f ⁴ 6s? 4f ⁴ 6p, ?1 mK; 4f ⁴ 6s? 4f ³ 5d ², ?30 mK. These values are in good agreement with calculated values of ?1.1 and ?30.6 mK.     

Changes in mean-square nuclear charge radii in Er from optical isotope shifts by laser-atomic-beam spectroscopy

High-resolution laser-atomic-beam spectroscopy has been applied to investigate transitions 4f ¹² 6s ²?4f ¹¹ 5d6s ² and transitions starting from metastable states of the configuration 4f ¹¹ 5d6s ² of Er I. Precise values for the transition isotope shifts and for the hyperfine constants of 10 levels belonging to the configuration 4f ¹¹ 5d6s² and 9 levels belonging to high lying even-parity levels have been determined. From the isotope shift data relative changes of mean-square nuclear charge radiiδ 〈r ²〉 for all the stable Er isotopes have been deduced: ¦168,170¦ 1, ¦166,168¦ 0.984(15), ¦164,166¦ 0.984(15), ¦162,164¦ 1.198(18), ¦166,167¦ 0.3357(50). Absoluteδ 〈r ²〉 values have been obtained by calibrating the optical data with a value from muonic x-ray spectroscopy: ¦168,170¦ 0.121 (10) fm². The odd-even staggering parameter for¹⁶⁷Er has been determined: 0.683(10). Our results are compared with experimental data from electronic x-ray spectroscopy and data from calculations with the extended liquid-drop and the droplet model.     

Nuclear moments and optical isotope shifts of108m Ag and110m Ag

The hyperfine structure of the resonance lines of^108m Ag and^110m Ag has been investigated by means of optical interference spectroscopy. The metastable isotopes were produced by neutron irradiation in a reactor. From the measureda- andb-values we derive the value for the nuclear magnetic dipole moment of^108mAgμ _I (108m)=3.577 (20)μ _n and the values for the electric quadrupole momentsQ _I (108m)=1.52(8) bQ _I (110m)=1.65(10) b (without Sternheimer correction). The measured isotope shifts allow the determination of the changes in the mean square charge radii of the nuclei involved:δ 〈r ²〉(108m-107)=0.022(3)fm² δ 〈r ²〉(110m-109)=0.029(2)fm². The isotope positions show odd-even staggering comparable with those of neighbouring isotonic nuclides.     

Changes in mean square nuclear charge radii from optical isotope shifts of long chains of isotopes

Results of recent measurements on isotope shifts are compiled for 20 chains of isotopes, mostly concerning short-lived radioactives. Unpublished material is also included. The σ <r²> are re-evaluated by using an improved calculation of the electron density at the nucleus. Therefore, in some elements, minor changes occur as compared to results given in the literature.     

AB initio calculation of isotope shifts in BaII

Hartree-Fock and pseudo-relativistic Hartree-Fock calculations have been made for the 6s, 5d and 6p configurations of BaII and used to provide estimates of screening effects and specific mass isotope shifts for the 6p-5d transition.     

Extended measurements of isotope shifts in Mg I

The isotope shifts in the Mg I transitionsλ 2,852 Å (3s ^{2 1} S ₀-3s3p ¹ p ¹ P ₁) andλλ 3,829, 3,832 and 3,838 Å (3s3p ³ P-3s3d ³ D) have been measured for²⁴Mg,²⁵Mg and²⁶Mg. The measurements were carried out using a pressure scanned Fabry-Perot interferometer and separated isotopes excited in hollow cathode discharge tubes. The results are compared to theoretical predictions and an attempt is made to convert measured line shifts into level shifts.     

Experimental determination of isotope shifts in Mg I

The isotope shift in the Mg l transitionsλλ 5167, 5172 and 5183Å (3s3p ³ P-3s4s ³ S) andλ 5528 Å (3s3p ¹ P 3s4d ¹ D) has been measured for the isotopes²⁴Mg,²⁵Mg and²⁶Mg. The hyperfine structure of theλ 5167 Å line has been studied and theA andB factors for the 3s4s ³ S ¹ level in²⁵Mg determined. The measurements were made with separated isotopes using a scanning Fabry-Perot interferometer.     

Dielectronic resonance method for measuring isotope shifts

Long standing problems in the comparison of very accurate hyperfine-shift measurements to theory were partly overcome by precise measurements on few-electron highly charged ions. Still the agreement between theory and experiment is unsatisfactory. In this Letter, we present a radically new way of precisely measuring hyperfine shifts, and demonstrate its effectiveness in the case of the hyperfine shift of 4s1/2 and 4p1/2 in 207Pb53+. It is based on the precise detection of dielectronic resonances that occur in electron-ion recombination at very low energy. This allows us to determine the hyperfine constant to around 0.6 meV accuracy which is on the order of 10%.     

Probing new intra-atomic force with isotope shifts

In the development of atomic clocks, some atomic transition frequencies are measured with remarkable precision. These measured spectra may include the effects of a new force mediated by a weakly interacting boson. Such effects might be distilled out from possible violation of a linear relation in isotope shifts between two transitions, as known as King’s linearity, with relatively suppressed theoretical uncertainties. We discuss the experimental sensitivity to a new force in the test of the linearity as well as the linearity violation owing to higher-order effects within the Standard Model. The sensitivity to new physics is limited by such effects. We have found that, for \(\hbox {Yb}^{+}\), the higher-order effect is in the reach of future experiments. The sensitivity to a heavy mediator is also discussed. It is analytically clarified that the sensitivity becomes weaker than that in the literature. Our numerical results of the sensitivity are compared with other weak force search experiments.     

Resolving pm wavelength shifts in optical sensing

The reflection or transmission properties of one and two-dimensional photonic crystals are widely used for optical sensing applications. A variety of optical sensors exist that change their optical properties upon receiving a stimulus. A compact wavelength detector capable of resolving very small changes in the spectral output of these sensors is highly desirable. A photodiode array (PDA) or position sensor device (PSD) in combination with a linear variable band-pass filter constitutes a very robust and compact device to detect those changes. The filter converts the wavelength information of the incident light into a spatial intensity distribution that is analyzed by the photodetector. We have investigated the performance of these wavelength detectors depending on the optical properties of the filter. This includes the gradient with which the transmission peak shifts across the filter surface and the spectral width of the transmission function. Also, we point out differences between the PDA and the PSD and analyze the influence of inhomogeneous illumination on the unit. PACS 42.68.Ay; 42.79.-e; 42.81.Pa     

Effects of nuclear polarizability on isotope shifts in electronic atoms

The isotope shift in electronic atoms is calculated in second order perturbation theory. We consider multipole ordersλ=0, 1 and 2 forZ=20–82 nuclei. To a good approximation it is directly proportional to the electron density at the nucleus. We study whether the polarization effect modifies the extraction ofδ〈r ²〉 values from isotope shifts measurements and find it to be small but not always negligible. Relative to the volume effect, the polarizability is of the same order of magnitude for electronic as well as muonic atoms.     

Vibrational isotope shifts in the B-X system of CL2

Excitation of resolved rovibrational (υ = 5, 8, 12, 13, 24, 25 and 26) states of Cl₂ B³Π(O⁺_u) has been carried out using a narrow-band Nd-YAG pumped dye laser. Excitation spectra for several bands of the B-X system of Cl₂, showing rotationally resolved lines, have been obtained by scanning the frequency of the dye laser. Complete rotational analyses have been carried out for the two isotopic species ³⁵Cl³⁵Cl and ³⁵Cl³⁷Cl. Vibrational isotope shifts have been calculated and discrepancies with observed values, for transitions involving levels above the onset of predissociation, are discussed.     

Volume isotope shifts in low lying transitions of Au I

Electronic factors in the volume isotope shift have been calculated in anab initio way with the relativistic Dirac-Fock method for a number of different optical single/and two-photon transitions in Au I. The agreement with a semi-empirical method is within 10% for the resonance transition. For this one and a few other transitions the effect of core excitation has been analyzed with the Multi-configuration Dirac-Fock method as well, and it was found to reduce the electronic factor in the order of 5%.     

Nuclear compression modulus and isotope shifts of Pb nuclei

Isotope shifts of Pb nuclei are studied by taking into account giant monopole and quadrupole resonance by a perturbative method. Giant monopole states are calculated by the HF + RPA response function method using three parameter sets of the Skyrme interactions SGI, SGII and SIII which give the compression moduli K_∞ = 269 MeV, 217 MeV and 356 MeV, respectively. Our calculations reproduce the kink of the observed isotope shifts at ²⁰⁸Pb, while the second-order effect due to the giant quadrupole resonances is not enough to explain the observed odd-even staggering. The Skyrme force SGII having K_∞ = 217 MeV shows the best quantitative agreement among three forces in comparison with the experimental data of the isotope shifts of Pb nuclei. The effect of the effective mass is also discussed.     

Optical isotope shifts of146Sm and151Sm

We have measured the optical isotope shifts of¹⁴⁶Sm and¹⁵¹Sm by laser resonance fluorescence. From these measurements the changes in the mean square nuclear radii are: Δ〈r²〉 (A=144 to 146)=0.266(10) fm², and Δ〈r²〉 (A=151 to 152)=0.262(10) fm². These results, together with those of the stable isotopes, show that the average nuclear expansion of samarium can be accounted for by the liquid drop model with deformations.     

Hyperfine structure and isotope shifts in near-infrared transitions of atomic nitrogen

We have obtained Doppler-free spectra of transitions in the → 2p²(³P) and → multiplets of atomic nitrogen using saturated absorption spectroscopy. These multiplets consist of respectively of seven and eight transitions, and have center of gravity wavelengths of 821 nm and 869 nm. Values for the hyperfine structure coupling constants of all the upper and lower states for these multiplets were obtained for both ¹⁴N and ¹⁵N. Isotope shifts of three transitions in each multiplet were also measured, and a significant J-dependence to the shifts was observed.     

Radial mode dependence of optical beam shifts

It is known that orbital angular momentum (OAM) couples the Goos-H?nchen and Imbert-Fedorov shifts. Here, we present the first study of these shifts when the OAM-endowed LG(?,p) beams have higher-order radial mode index (p>0). We show theoretically and experimentally that the angular shifts are enhanced by p while the positional shifts are not.